MRI technology utilizes magnetism and radio frequency to create three-dimensional sections or layered images of body organs or tissue for medical diagnosis and research. These images greatly improve the ability of doctors to distinguish abnormal from healthy tissues. MRI can also be used to observe and measure dynamic physiological changes inside a patient without cutting into or penetrating the body. Conventional MRI devices consist of a closed tube into which the patient is inserted for the purpose of the examination. To produce an image, an MRI device uses a powerful magnet to generate a magnetic field. When a patient lies within this field, the nuclei of atoms within the body align themselves with the magnetic field. Radio waves are then pulsed through the body, causing the nuclei to change their alignment with respect to the axis of the magnetic lines of force. As they return to their previous state after each pulse, they produce faint, distinctive radio signals; the rate at which they emit signals and the frequency of the signals depend on the type of atom, the temperature, the chemical environment, position, and other factors. These signals are detected by coils around the body and processed by a computer to produce images of internal structures. Radiofrequency coils are a major part of the radiofrequency (RF) system in the magnetic resonance imaging hardware. They consist of two electromagnetic coils, the transmitter and receiver coils generating and receiving electromagnetic fields. The receiver coil picks up the RF electromagnetic radiation produced by nuclear relaxation inside the subject
There are two major types of RF coils: volume coils and surface coils. Volume coils are configured to provide a homogeneous RF excitation across a large volume. Most clinical MRI scanners include a built in volume coil to perform whole-body imaging, and smaller volume coils have been constructed for the head and other extremities. These coils require a great deal of RF power because of their size, so they are often driven in quadrature in order to reduce by two the RF power requirements. Further, volume coils are undesirable when scanning a small area because they receive noise from the entire volume, not just the region of interest.
Surface coils are designed to provide a very high RF sensitivity over a small region of interest. These coils are usually placed directly over the anatomy of interest. The surface coils make good receivers as they detect noise only from the area of interest, but they provide low RF homogeneity if used for transmission.
U.S. Pat. No. 8,217,653 B2, filed 20 Feb. 2009 titled: “MULTI-CHANNEL RF COIL SYSTEM WITH MULTI-CHANNEL RF COIL TRANSCEIVER DETECTING MORE THAN ONE FREQUENCY AT THE SAME TIME FOR MAGNETIC RESONANCE IMAGING SYSTEMS AND METHODS”, discloses an RF coil system for magnetic resonance applications includes a multi-channel RF coil transceiver and a multi-channel RF coil. The RF coil system is structured for reconfiguration between a plurality of operational modes.
US Pat. application 20140055136 A1, filed 13 Apr. 2012 titled “MULTICHANNEL RF VOLUME RESONATOR FOR MRI”, discloses an RF volume resonator system comprising a multi-port RF volume resonator, like e.g. a TEM volume coil or TEM resonator, or a birdcage coil, all of those especially in the form of a local coil like a head coil, or a whole body coil, and a plurality of transmit and/or receive channels for operating the multi-port RF volume resonator for transmitting RF excitation signals and/or for receiving MR relaxation signals into/from an examination object or a part thereof.
U.S. Pat. No. 8,390,288 B2, filed 24 Apr. 2008, titled: “METHOD AND RF TRANSMITTER ARRANGEMENT FOR GENERATING RF FIELDS”, discloses a multi-channel RF transmitter arrangement comprising a plurality of RF transmitter elements like RE antennas, antenna elements, coils or coil elements, for generating an RF field, especially for use in a magnetic resonance imaging system for exciting nuclear magnetic resonances, and a method for generating such an RF field wherein the RF transmitter elements are segmented in a plurality of segments at least along the direction of one or more of the main magnetic field of the MRI system, the z-direction or the longitudinal direction.
With the increasing number of premature births and good surviving prognosis for premature neonates born at an early gestation age as 24 weeks the need for neonates imaging techniques, such as magnetic resonance imaging, that are noninvasive and do not involve ionizing radiation for their function.
When considering magnetic resonance imaging of neonates several parameters and precautions must be considered. New born and ill babies are usually kept in an incubator especially designed for maintaining constant environmental conditions such as temperature and humidity fitting for life supporting the baby. In addition in the incubator, functioning as an intensive care unit, provides the baby with connections to various medical devices and monitors to facilitate and overview breathing, feeding, fluid exchange and cardiac activity. Babies and neonates are also sensitive to excess light, noise, vibration and handling, and so these must be minimized to benefit recovery. Any transfer or movement of the baby may require the transfer or reconnection of attached medical devices, posing an additional stress on the baby. Further, any changes in location of the neonate may expose him to infection from an unprotected environment. The neonate must be kept in a life supporting environment, usually connected to life supporting equipment and monitoring devices, in order to maintain respiratory and cardiovascular functions, body temperature, and fluid and electrolyte homeostasis.
Since MRI imaging utilizes a strong magnet, care must be taken to insure that all elements and equipment in the vicinity of the MRI are ‘MRI safe’, meaning that they are not magnetic, not conductive, and not RF reactive. Many accidents were reported when metallic items were pulled in by the force of the magnetic field and harmed a patient during imaging. Another important parameter is to insure that the permeability of materials surrounding the neonate (for example the incubator material) to magnetic fields and radio frequency waves, is such that it does not disturb the image received.
Other risks may be peripheral nerve stimulation, exposure to a loud noise (up to 120 dB), generated by the rapid switching of the magnetic field gradients, or overheating may occur due to absorption of the energy that is utilized to generate the magnetic spin. This risk is especially enhanced considering the neonate's high ratio of surface area to body volume, and their immature body temperature regulation. Thus, neonates should be kept in an MRI-safe incubator providing a life supporting internal environment, and further buffering the conditions of the external environment such as noise, light, temperature, humidity, and etc.
Another risk involves an unintentional shut-down of a superconducting electromagnet (“quench”), resulting in the rapid boiling of liquid helium from the device. The rapidly expanding helium if released into the scanner room may cause displacement of the oxygen and present a risk of asphyxiation. In order to minimize risks and maintain homogenous conditions, a constant low temperature is kept in the MRI room. Further, to limit complications, the neonate should be kept in a device enabling easy access and rapid evacuation if needed.
Magnetic resonance devices are usually placed in dedicated especially designed RF shielded rooms, necessitating the transfer of neonates in need of a scan to a remote location. It is a long felt need to transport between a premature neonate intensive-care ward and an MRI imaging facility, without decoupling and disconnecting the premature neonate from life-support systems, and executing the imaging process with as little handling of the neonate as possible.
The known MRI compatible incubators, such as those manufactured by Advanced Imaging Research (Cleveland, Ohio), that are equipped with RF coils require the transfer of the neonate from a standard intensive care incubator into the MRI compatible incubator. In these arrangements, the RF coils are stationary in position after installation, and do not enable temporary position shifting for accessing the neonate. Another commercially available magnetic resonance compatible incubator is the Lammers Medical Technology GmbH (LMT), in which the head coil is available only as an accessory completely detachable from the incubator. This accessory requires the movement of the neonate in order to be installed. Further the LMT MRI compatible incubator needs to be lifted from the trolley and inserted into the open bore.
The RF coils known in the art cannot be installed on an MRI compatible incubator such that the RF coil can be easily manipulated in at least two vectors, between two positions, without moving the neonate in order to install the coil, position it, or for the imaging process.
There is a long felt and an unmet need to provide an MRI-compatible neonate's cradle, cart, and/or MRI-cart-cradle assembly comprising a maneuverable RF coil and methods for both (i) applying an RF coil over a neonate immobilized within his/her cradle and (ii) conveniently removing the RF coil from the neonate and safely placing it when it is not required for imaging.